Malaria: RTS,S and R21 Vaccine Evidence

Malaria burden in sub-Saharan Africa, the development of RTS,S/AS01 (Mosquirix) vaccine, WHO recommendation in 2021, efficacy data, and the newer R21/Matrix-M candidate.

Parasitic Vaccine NEW (2021) Sub-Saharan Africa

Global Disease Burden

Malaria is a life-threatening parasitic disease caused by Plasmodium parasites, transmitted through the bite of infected female Anopheles mosquitoes. It is preventable and treatable, yet it continues to impose a devastating toll on human health worldwide.

The disease disproportionately affects young children and pregnant women in sub-Saharan Africa, where transmission is year-round and the parasite burden is highest.

2022 Global Statistics

  • ~247 million malaria cases globally
  • ~619,000 deaths globally
  • 95% of deaths in African region
  • ~80% of deaths are children under 5

RTS,S/AS01 (Mosquirix™) Vaccine

After decades of development, RTS,S (brand name Mosquirix) became the first malaria vaccine to receive WHO recommendation in October 2021. It targets Plasmodium falciparum, the deadliest malaria parasite.

Phase III Trial Efficacy Data

The pivotal trial (ClinicalTrials.gov NCT00866619) enrolled ~15,000 children across 7 African countries:

36%
Efficacy in children 5-17 months (4 doses over 18 months)
26%
Efficacy in infants 6-12 weeks (4 doses)
~40%
Reduction in severe malaria cases

Pilot Implementation

WHO coordinated pilot implementation programs in Ghana, Kenya, and Malawi from 2019-2022, demonstrating feasibility of delivering a 4-dose childhood vaccine in routine immunization programs.

WHO Recommendation

In October 2021, WHO recommended widespread use of RTS,S in children living in areas with moderate to high P. falciparum malaria transmission. This was a historic milestone as the first vaccine against a parasitic disease.

R21/Matrix-M: The Next Generation

The R21 vaccine, developed by the University of Oxford and manufactured by Serum Institute of India, represents a next-generation malaria vaccine with higher efficacy potential.

Phase III Trial Results

  • 75% efficacy at 12 months (seasonal delivery)
  • 68% efficacy at 12 months (standard schedule)
  • Trial enrolled ~4,800 children in Burkina Faso, Kenya, Mali, Tanzania

Key Differences from RTS,S

  • Uses Novavax Matrix-M adjuvant (same as in COVID-19 vaccine)
  • Lower antigen dose per shot
  • Potentially lower cost (~$5/dose vs ~$40/dose)
  • WHO prequalification expected 2024

Sources & Citations

  • WHO. (2022). Malaria - Key Facts. who.int
  • RTS,S Clinical Trials Partnership. (2015). Efficacy and Safety of RTS,S/AS01. Lancet, 386(9988), 31-45.
  • Datoo, M.S., et al. (2024). High Efficacy of R21/Matrix-M Vaccine. Lancet.

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